Method of controlling auto white balance

1. A method of controlling auto white balance, the method comprising; converting a color space of an input image from an RGB color space into a YCbCr color space; dividing the input image into a plurality of divided regions; selecting a predetermined number of divided regions in order determined by mean values of Y of pixels included in the plurality of divided regions; comparing a predetermined threshold value with the number of pixels having values of Cb and Cr within a predetermined Cb-Cr range among the pixels included in the selected divided regions in order to determine a white area; and calculating auto white balance gains by using mean values of Y, mean values of Cb, and mean values of Cr of the pixels included in each of the selected divided regions when the number of pixels within the predetermined Cb-Cr range is greater than the threshold value.

2. The method of claim 1 , further comprising: selecting additional divided regions greater than the predetermined number in order determined in the selecting the divided regions when the number of pixels within the predetermined Cb-Cr range is smaller than the threshold value, wherein the comparing the predetermined threshold value with the number of pixels comprises comparing the predetermined threshold value with the number of pixels having values of Cb and Cr within the predetermined Cb-Cr range among the additionally selected divided regions and the divided regions selected in the selecting of the divided regions.

3. The method of claim 1 , wherein the selecting the divided regions comprises: outputting a mean value of Y of the pixels included in each of the plurality of divided regions; applying weight to the output mean value of Y according to whether each of the divided regions is located; and selecting the predetermined number of divided regions according to the magnitude of the mean values of Y applied with the weight.

4. The method of claim 3 , wherein in the applying the weight, the less weight is applied to a divided region located at the edge of the input image.

5. The method of claim 1 , wherein the predetermined Cb-Cr range used in the comparing the predetermined threshold value with the number of pixels is varied according to each of the selected divided regions on the basis of the mean value of Y of the pixels included in each of the selected divided regions.

6. The method of claim 5 , wherein the predetermined Cb-Cr range becomes narrower when a divided region has a higher mean value of Y.

7. The method of claim 1 , wherein the outputting the auto white balance gains comprises: converting the mean values of Y, the mean values of Cb, and the mean values of Cr of the pixels included in the selected divided regions into mean values of R, mean values of G, and mean values of B; and determining auto white balance gains of values of R and B of the input image as “mean values of G/mean values of R” and “mean values of G/mean values of B”.